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Sensors 2017, 17(12), 2842;

High-Speed Focus Inspection System Using a Position-Sensitive Detector

Department of Laser and Electron Beam Application, Korea Institute of Machinery & Materials (KIMM), Daejeon 34103, Korea
Department of Nano-Mechatronics, Korea University of Science and Technology (UST), Daejeon 34113, Korea
Department of Material Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
Author to whom correspondence should be addressed.
Received: 30 October 2017 / Revised: 4 December 2017 / Accepted: 4 December 2017 / Published: 8 December 2017
(This article belongs to the Special Issue Charge-Coupled Device (CCD) Sensors)
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Precise and rapid focus detection is an essential operation in several manufacturing processes employing high-intensity lasers. However, the detection resolution of existing methods is notably low. This paper proposes a technique that provides a rapid-response, high-precision, and high-resolution focus inspection system on the basis of geometrical optics and advanced optical instruments. An ultrafast interface position detector and a single-slit mask are used in the system to precisely signal the focus position with high resolution. The reflected images on the image sensor are of a high quality, and this quality is maintained persistently when the target surface is shifted along the optical axis. The proposed system developed for focus inspection is simple and inexpensive, and is appropriate for practical use in the industrial production of sophisticated structures such as microcircuits and microchips. View Full-Text
Keywords: focal position detection; laser micromachining; CCD camera; single-slit masks; position-sensitive detector focal position detection; laser micromachining; CCD camera; single-slit masks; position-sensitive detector

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Cao, B.X.; Hoang, P.L.; Ahn, S.; Kang, H.; Kim, J.; Noh, J. High-Speed Focus Inspection System Using a Position-Sensitive Detector. Sensors 2017, 17, 2842.

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